Large, stationary, so-called “legacy” natural gas fuel burning, reciprocating piston, combination or integrated internal combustion engines and compressors driven by such engines have been used to pump natural gas through distribution pipelines for more than 100 years following conversion of such compressor engines to burn natural gas fuels instead of liquid fuels or steam.
Some layouts of such combination engine-compressors can be observed in patents to Mueller U.S. Pat. No. 2,514,287; Scheiterlein U.S. Pat. No. 2,917,226; and Heater et al. U.S. Pat. No. 4,091,772. More recent examples of the combustion chamber arrangement of such engines can be observed in pending U.S. patent application publication US 2010/0319655 of McClendon. Additional description of the legacy engines can be found in the report sponsored by Engines and Energy Conversion Lab entitled “ERLE Cost Study of the Retrofit Legacy Pipeline Engines to Satisfy 1/2 g/BHP-HR NOx”, Rev. 1, May 21, 2009, involving a study performed by Engines and Energy Conversion Lab, National Gas Machinery Laboratory (An Institute of Kansas State University), Advance Technology Corporation and Hoerbiger.
A further review of legacy Cooper-Bessemer Type GMV Integral-Angle Gas Engine-Compressors may be found at “An ASME Historic Mechanical Engineering Landmark” published by the ASME History and Heritage Committee in August 2006 for Knox County Historical Museum, Mount Vernon, Ohio. Another publication describing such engines may be observed in Bourn, Gingrich, and Smith's “Advanced Compressor Engine Controls to Enhance Operation, Reliability and Integrity”, Southwest Research Institute, San Antonio, Tex., USA, per Doe Award No. DE-FC26-03NT41859, SwRi Project No. 03.10198, March 2004.
Legacy engines of the type discussed above have served well and continue in service up to the present time. On the other hand, they still suffer from certain disadvantages that have required further study and research to overcome. To name a few such disadvantages, the engines are prone to be difficult to start when cold; run roughly when cold, with mechanical stresses imposed on moving parts such as pistons and bearings and with preignition events that damage spark igniters; run with relatively high variation of peak firing pressure and variation of timing of peak firing pressures of combustion cycles; emit excess NOx, unburned hydrocarbons and excess CO; and run at efficiencies that are less than theoretically possible due to compromises imposed on the operating conditions of the engines.
Thus, a review of reciprocating piston, internal combustion engine art reveals various attempts to improve lean-burn combustion in the combustion chamber of such engines by utilizing prechambers to initiate a torch-like output to cause ignition in lean-burn fuel-air mixtures.
There is thus a need for improved combustion chamber design for such engines to overcome or avoid the described disadvantages and to bring the emissions of the engines into line with modern emission standards. Obtaining such improvements, however, must not come at a cost of excess downtime for the engines, which operate around the clock, or major modifications of the engine components which would require costly and lengthy trials and research to prove feasibility and demonstrate successful results. Such engines are no longer manufactured, and repair and overhauling of the engine often require manufacturing parts to replace worn out elements and components that are no longer readily available.